Blend the papaya flesh in a blender until it becomes a smooth purée.
Whip 150ml of double cream with vanilla seeds until stiff peaks form.
Fold the papaya purée into the whipped cream and chill the mixture.
Heat the caster sugar in a frying pan until it begins to caramelize.
Add the raisins and cook gently until the caramel bubbles.
Stir in the butter and then the remaining 75ml of cream once melted.
Cook for several minutes until the sauce thickens and turns golden-brown.
Spoon the sauce into a glass and top with the chilled papaya mousse.
Garnish the dessert with a fresh sprig of mint.